1. Technical Field
The present invention relates to an information recording apparatus for recording and reproducing an information signal on and from a recording disc.
2. Description of the Related Art
At present, CD-R, CD-RW, DVD-R, DVD-RW or the like is known as an optical recording disc on which information data can be written.
FIG. 1 illustrates the schematic configuration of a disc recorder for writing information data on such recording disc.
In FIG. 1, a recording/reproducing head 2 irradiates a writing light beam onto a recording surface of a recording disc 3 such as CD-R, CD-RW, DVD-R or DVD-RW so as to record information data supplied from a recording/reproducing control circuit 10 on the recording disc 3. The recording/reproducing head 2 receives a reflected light beam the recording surface of the recording disc 3 when a reading light beam is irradiated there onto, and opto-electrically transduces the reflected light into a read signal which is in turn supplied to the recording/reproducing control circuit 10. The recording/reproducing control circuit 10 reproduces information data having recorded on the recording disc 3 based on the read signal, and supplies the reproduced information data to the succeeding stage. A slider unit 4 transfers the recording/reproducing head 2 in a radial direction of the recording disc 3 in accordance with a slider drive signal supplied from the recording/reproducing control circuit 10.
Then, when new information data is to be additionally recorded on the recording disc, the disc recorder first searches the recording disc for a boundary position between a recorded region in which information data has previously been recorded and an unrecorded region Then, the disc recorder starts writing information data from the boundary position, i.e., the leading point of the unrecorded region.
FIG. 2 shows the operation performed by the conventional disc recorder illustrated in FIG. 1 for searching for a boundary position.
Assume herein that the recording disc 3 loaded in the disc recorder includes a recorded region, as indicated by batching, in FIG. 2A, in which information data has previously been recorded, and an unrecorded region.
The recording/reproducing control circuit 10 first drives the slider unit 4 to start a forced transfer of the recording/reproducing head 2 from the innermost periphery to the outer periphery of the disc 3. In this manner, a transfer speed of the recording/reproducing head 2 toward the outer periphery of the disc 3 gradually increases as shown in FIG. 2B, and reaches a predetermined constant speed V1. Meanwhile, the recording/reproducing control circuit 10 fetches a read signal captured by the recording/reproducing head 2, and determines at all times whether or not an RF (high frequency) signal carrying information data exists in the read signal. In this event, when an RF signal exists, this means that the recording/reproducing head 2 is passing above a recorded region shown in FIG. 2A, and when no RF signal exists, this means that the recording/reproducing head 2 is passing above an unrecorded region. Thus, the recording/reproducing control circuit 10 controls the slider unit 4 to stop the transfer movement of the recording/reproducing head 2 if it finds a transition from a state in which an RF signal exists to a state in which no RF signal exists in the read signal in response, the slider unit 4 gradually reduces the transfer speed of the recording/reproducing head 2, as shown in FIG. 2B, immediately after passing a boundary position NWA between the recorded region and unrecorded region shown in FIG. 2A. In this manner, the recording/reproducing head 2 jumps over the boundary position NWA and stops at a position P in the unrecorded region, as shown in FIG. 2B (first scan RFEND search).
A shown in FIG. 2C, the recording/reproducing control circuit 10 controls the slider unit 4 to transfer the recording/reproducing head 2 from the position P in the inner peripheral direction of the disc at a speed V2 lower than the constant speed V1. In this manner, the recording/reproducing head 2 is transferred in the inner peripheral direction of the disc, and the transfer speed reaches a constant speed V2 as shown in FIG. 2C. Meanwhile, the recording/reproducing control circuit 10 fetches a read signal captured by the recording/reproducing head 2, and determines at all times whether an RF signal carrying information data exists in the read signal. In this event, the recording/reproducing control circuit 10 controls the slider unit 4 to stop transferring the recording/reproducing head 2 if it detects a transition from a state in which no RF signal exists to a state in which an RF signal exists in the read signal. In this manner, the recording/reproducing head 2 gradually reduces the transfer speed in the inner peripheral direction of the disc immediately after passing the boundary position NWA, and stops at a position Q in the recorded region (second scan RPEND search).
Next, the recording/reproducing control circuit 10 drives the slider unit 4 to jump the recording/reproducing head 2 track by track in the outer peripheral direction of the disc as shown in FIG. 2B. Meanwhile, each time the recording/reproducing head 2 jumps one track, the recording/reproducing control circuit 10 determines whether or not an RF signal exists in the read signal captured by the recording/reproducing head 2 in this event, it is to be noted that the recording/reproducing head 2 reaches above the boundary position NWA when the recording/reproducing control circuit 10 finds a transition from a state in which an RF signal exists to a state in which no RF signal exists. Thus, upon detection of the transition from a state in which an RF signal exists to a state in which no RF signal exists, the recording/reproducing control circuit 10 controls the recording/reproducing head 2 to stop the one-track jumping operation and start writing information data from that position.
As described above, the conventional disc recorder makes the first scan RFEND search as shown in FIG. 2B for transferring the recording/reproducing head 2 to the boundary position NWA of the recorded region, and subsequently makes the second scan RFEND search as shown in FIG. 2C. Then, as the distance between a current position of the recording/reproducing head 2 and the boundary position NWA is reduced to some degree by these scan RFEND searches, the one-track jumping operation is repeated as shown in FIG. 2D to bring the recording/reproducing head 2 above the boundary position NWA.
However, as the scan RFEND searches are made in repetition, a problem arises that it takes a long time after the issuance of a recording command until the start of an actual recording operation on the recording disc.